GPS and other turn-by-turn navigation systems are becoming ever more prevalent as tools for determining a route to a particular destination. For example, a TOMTOM GPS is often a portable GPS that can be moved from vehicle to vehicle. Using satellite GPS signals, it determines where its present location on the globe is. This information is then combined with map and or heading information to determine a route to a selected destination.
Some vehicles also have built in GPS, and use, for example, an instrument display screen to display a route and/or directions. In other systems, directions can be spoken by a vehicle system to a driver, in lieu of or in addition to being displayed.
In general, GPS systems will determine a present location of a vehicle, determine a map location that corresponds to that present location, a provide directions from there. Of course, if the map data is incomplete or, for example, the vehicle is parked in the middle of a hay field, traditional “map directions” may not be available to the system on which directions to the driver can be based.
In addition to these situations, there are many “urban hayfields,” in the form of parking lots, driveways, etc. whose location does not conform to any particular map location in GPS data. One solution would be to program all of these into a GPS map, but since they are prone to change and arise quite often, this may be a difficult task to undertake.
Accordingly, GPS systems need some method of “guessing” to determine how a vehicle is to get from a present “unknown” location to a location along a route to be traveled.
Additionally, some vehicle-based computing systems, such as the FORD SYNC system, may not store all of the map data in the vehicle, since storage space may be limited and needed for a variety of applications. As a result, relevant data about a certain area to be traveled may be dynamically transmitted in small packets. Since the vehicle may not be holding the entire map of an area, it is also useful to have a method for determining and/or providing directions to a route to be traveled from an unknown location.
As one example, if a vehicle is in parking lot 201 shown in FIG. 2, there could be a myriad of possibilities for getting to Main St. 209 (from which directions are provided). The system has no way of knowing that the user will take route 219, and, similarly, the system (using limited bandwidth), may not want to send enough information to cover all possible routes from the parking lot 201 to Main St. 209. Accordingly, it may be desired to have a method for providing a user with simple directions that do not require total knowledge of all possible routes.